Triple-negative breast cancer (TNBC) is less common than other types of breast cancer, tends to be more aggressive, and has fewer treatment options (though treatment options are improving). It is called "triple-negative" because the cancer cells test negative for estrogen receptors (ER), progesterone receptors (PR), and HER2 proteins. TNBC will not respond to hormone therapies or HER2-targeted drugs, which are common treatments for other types of breast cancer.
For early-stage and locally advanced TNBC, most treatment plans will include surgery to remove the tumor (lumpectomy) or remove the entire breast (mastectomy). Surgery will also be used to remove any lymph nodes affected by the cancer. The type of procedure recommended and the amount of breast tissue removed will depend on multiple factors, and a healthcare team will be your best source of information about surgery options and surgery recommendations.
In most cases, a person will receive additional cancer treatments before and/or after surgery.
Treatment before surgery
A treatment used before surgery is called a neoadjuvant therapy. The main goal of a neoadjuvant therapy is to shrink the size of the tumor, which will make it easier to remove during surgery. In some cases, shrinking a tumor may mean that the cancer can be removed with a lumpectomy.
Another goal of neoadjuvant therapy is to treat micrometastatic disease as early as possible. Micrometastatic disease refers to cancer cells that have already spread beyond the breast but have not yet formed sizable tumors that can be found with imaging tests.
Neoadjuvant therapy can also provide a cancer care team with information that can help guide future decisions in treatment—it allows them to see how the cancer responds to a cancer drug, which can inform what cancer therapies are recommended following surgery.
What neoadjuvant therapies are used to treat TNBC?
Neoadjuvant therapies for TNBC may include chemotherapy, or a combination of chemotherapy and an immune checkpoint inhibitor.
Chemotherapy refers to drugs that contain chemicals that are effective at killing cancer cells or stopping cancer cells from dividing. It is the main systemic therapy used in the treatment of TNBC—a systemic therapy is a therapy that acts on cancer cells throughout the body. Chemotherapy is usually the first treatment used for metastatic TNBC, where the cancer has spread to other parts of the body and cannot be treated with surgery
Immune checkpoint inhibitors are a type of immunotherapy, a treatment that helps the body's immune system detect and eliminate cancer cells. Immune checkpoint inhibitors work by disabling immune checkpoints. These are proteins that are normally found on healthy cells that send a “don’t attack us” signal to the immune system. Some cancer cells have large amounts of immune checkpoints, which act as a kind of disguise that helps them avoid detection by the immune system. Immune checkpoint inhibitors work by disabling that disguise.
Treatment after surgery
A treatment used after surgery is called an adjuvant therapy. Adjuvant therapy can help eliminate any cancer cells that remain after the surgery, such as cancer cells in nearby tissues or micrometastatic disease found in other areas of the body. The goal is to eliminate any cancer cells that could cause a recurrence (the cancer coming back after treatment).
What adjuvant therapies are used to treat TNBC?
Adjuvant therapies can include radiation therapy, chemotherapy, immunotherapy, or targeted therapy drugs called PARP inhibitors. Sometimes these therapies are used in sequence—for example, a person may have adjuvant chemotherapy followed by an additional adjuvant therapy with a targeted drug.
Adjuvant therapies are part of an overall plan for treatment that will also include monitoring and follow-up care. TNBC is more likely to recur compared to other types of breast cancer. A healthcare team will put together a schedule for checkups and tests to look for signs of recurrence after treatment is completed.
Making treatment decisions
Many factors are considered when a healthcare team recommends treatment for breast cancer, including the stage of the cancer, the tumor grade (how abnormal the cancer looks compared to healthy cells), the results of genetic testing (such as BRCA mutations), and how the cancer has responded to treatment.
The overall health and the preferences of the person being treated are other important factors to consider—and anyone diagnosed with TNBC is encouraged to take an active role in their treatment.
